Dynamo-electric machine



o cf, 23,1928. n 1,689,188

R. POHL ET AL DYNAMO ELECTRIC MACHINE l Filed March 29, 1927 Inventors:Robert, Pohl Henry G. Reist;`

b9 Theil*` Atorneg.

Patented Oct. a3, 1928.

Bonner Pom., or BERLIN, GERMANY, AND HENRY-e. nErsr, or sonENEc'rAnY,'

NEW YORK, AssIeNons ToeENEnAL ELECTRIC coMPANY,'A CORPORATION or NEWYORK..

nYNmo-ELECTBIG MACHINE'.

Appnanon me.; marchas, 192%,5seria1 No. 179,298, and 1n' Germany Aprn19, 192s.

Our invention relates generally todynarnoelectric machines and vhas forits ob]ect the provision of a magnetic conduct-ing path of lowyreluctance for the stray fieldflu'X pro- V .duced during.the'operation'thereof so that.'

excessive eddy current losses will be avoided;

The stray field producedzin the voperation of a dynamoelectricmachinemoves peripherally of the stator and synchronously. with thel mainfield. ,In order toz prevent edd'v' current losses occasioned by'thisstray field,

' in accordance with our invention, the stator l' laminations of fthemachine between the clamping members'are formed to facilitate .15 theentrance of the stray field flux thereintoin such directionthat'theresulting eddy currents'ar'e minimized.l

Our invent-ion will be morev fully explained v in the followingdescription by referring to and stator of a dynamo-'electric machine em--mentary sectional view of a slight modification of theI form o f ourinvention shownin Fig; 1.

dynamoelectric machine -l supports, the `stator laminations 2 which areclampedgin place-at each -end of the 'frame'by the 'clamping member 3.stator windings lpass hrovugh stator slots and end connections/P hereofextend peripherally of the stator and through other stator slotsin-accordance with the usual construction'. Awinding guard jis attachedto the: frame l-to protect' the lwindings and improve the generalappear'- ance of the machine. A rotor 6 is mounted with its peripheryclosely adjacent the staat 7 to 'afford a space for the windings 8 ofthe'rotor, which are retained in position vand enclosed by means of aring 9, insulated therefrom at 10, andan end ring l1'. In operation ofthe machine a rotatingstray field 1s producedas above referred to by the'windthe accompanying drawing, in which Fig.l 1 l is a fragmentarysectional view ofthe rotor tor laminations and is reduced' inl diameter'of the rotor, the conductors 4 and their vconnections A which isindicated in dotl ted linesv at A in the/drawing. This stray.

'rents-l therein, inasrnnch as the crossvsection of the laminationsaislarge transverselto the path of the stray field. flux, but this isprevented in our construction by arranging a' 55 group 2a-of statorlaminations whichfare of vthe sameffoutside diameter as the remainder ofthe statorjlaminations .andfwhich'ar ar.-

ranged between the clamping members Y3 adjacent thee idof the .stator atsuccessively '60 increasing istancesfrom the axis of the rotor, whichforms a series of steps steeply 1ncl1ned to thek rotor, as clearly showninlthe drawing. For the best results this inclination'shouldbesubstantial, at least 30 degrees 65 vto the axis vofthe rotor andpreferably t5 de-A r grees or more. If desired the edges of thelamlnatlons of'this group 2 may bebeveled 1 so as topresent a smoothsurface inclined relative to the rotor.` The-stator laminations 70 i areformed the usualmanner'by punching them out of sheets of varnishedmetal, and the stator-may be made up of aplurality of I I -k sectors ora pluralitfef annuli in accordance In Fig. 1 of the drawing the frame ofthe with the usual practice. It may be found con-I vement to make thelaminations of the group '2a of successively decreasing inside diameterfrom the end ofthe stator longitudinally thereof,ormere ly"to arrangelamination secf tors vat different' distances from the ,rotorCM 8.04 i

stator laminations in which eddy current $5,-

losses 4will be comparatively small.

'Inthe modification'illustrated in Fig.' 2.

of the drawing,l our invention is applied to v a dynamo-electric machinewherein theface ofthe ,rotor 6't carrying the useful fluir e2;-l 90tends longitudinally thereof adjacent the`v stepped group oflaminations, so that the stepped group of laminat-ions carry part of theuse-ful flux as well as the stray Afield flux.

rotor 6 and is reduced in diamete'rat to 'The rotor 6? is of similarconstruction to the 95 radially afford a space for the windings 8a. Thering 9 is insulated at 10a from the winding 8, forming with zthe ring11a and the rotor an enclosure for the ends of the winding. The frame llsupports the laminations 2 and the stepped group thereof 2a, which areclamped in the frame l of the machine between clamlping members 3, whichare arranged at tie ends of the frame, and the Winding guard 5 isemployed asy in the structure of Fig. l.

In operation of either of these forms of our invention a stray fieldflux is produced by the rotor and the windings as indicated by thedotted lines at A. This flux is directed toward the exposed ends of thestepped group of laminations, is distributed throughut them, and passestherethrough nd circumferentially as the stray field revlvessynchronouslywith the rotor. Thus it ill be clear that the stepping ofthe end grop of laminations makes them more eifectiv as a magnetic pathfor the end stray field ux and since the transverse section of theaminations along the path of the flux lbeing small, eddy vcurrent losseswill be minimized.

In the arrangement shown in Fig. l the active iron of the rotor 6 onlyextends as far as the group of laminations 2a of the statorA which isinclined to the rotor so that this group of laminations 2a serves onlyas a path for the stray flux. In the arrangement shown in Fig. 2,however, the active iron of the rotor 6 extends as far as the end of theinclined group of laminations 2a of the stator. In this arrangement thegroup of laminations 2 in addition to its function as a stray linxreturn path would also act as active iron. l

It will be seen from the foregoing descrip'- tion that our inventionmateriall reduces eddy current losses due to the end straylield flux ofa dynamo-electric machine, and we desire it to bevunderstood that ourinvention is not limited to the vparticular arrangement shown anddescribed, but we intend in the appended claims to cover all`modifications which do not depart from the spirit and scope of ourinventlonm Whatwe claim as new and desire to secure by Letters Patent ofthe United States, is,-

1. In a dynamo-electric machine, a stator including laminationstransversely aligned to form a surface adaptedto substantially conformto a rotor, clamping membersfor retaining said laminations in`saidstator, and/a group of said laminations between said clamping membersand adjacent the endI of the stator having their edges at differentdistances from the axis of the stator inorder to reduce eddy currentlosses due to V.end stray field fiux, said group .of laminations beingof' substantially the same outer diameter as said stator laminations.

2. In a dynamo-electric mach1ne,a rotor,

a stator including laminations forming a surface substantiallyconforming to the shape of the rotor, clamping members for retainingsaid laminations in the stator, and a roup of said stator laminationsbetween said c amping members and adjacent the end of the stator inwhich the laminations are at successively increasing distances from theaxis of the 4 rotor, thereby exposing the laminations of the Y therotor, clamping members for retainingsaid laminations in the stator, anda group of saidstator laminations between said clamping members andadjacent the end of the stator successively decreasing in diameter fromthe end of the stator longitudinally thereof, thereby forminga steepincline relative to the axis of said rotor in order to reduce the lossesdue to the end stray field flux, said group of laminations being ofsubstantially the same outer diameter as said stator laminations.

4.' In a dynamo-electric machine, a rotor, a stator includinglaminations formin a surface substantially conforming to the sape of therotor, clamping members for supportingl said laminations in said statorand a group of said stator laminations between said clamping members andadjacent the end of the stator successively decreasing in diameter fromthe end of the stator longitudinally thereof, the

. successive decrease in diameter of the laminationsof said group beingsuch as to-form an incline of at least 30 degrees relative to the axisof said rotor in order to reduce losses due to the end stray field flux,said group of laminations being'of substantially the same outer diameteras said stator laminations.

5. In a dynamo-electric machine, a rotor,

and a'stator including laminations that formv a surface substantiallyconforming to the shape of the rotor, clamping members for supportingsaid laminations in said stator, and a4 group of said stator laminationsbetween said clamping members and adjacent the end of the statorsuccessivel decreasing in diameter in steps from the en of the statorlongitudinally thereof, thereby forming a substantial radially steppedincline relative to said rotor in l order to reduce the losses due tothe end stray lao field flux, said group of laminations being ofsubstantially the same outer diameter as said stator laminations.

6. In,- a dynamo-electric machine, a rotor, and a stator includinglaminations forming a surface substantially conforming to the shapeofthe rotor, clamping members for supportzing said laminations in saidstator, and a group ftsaiamto'r lmimtias, between ggd l laminkizngwg fsubgntinuy the same. clamping "members, and adj'ao'lt' the end of outerdiametelfas' said stator laminations.

thestator suecessiv'ely-deoreasing'in diameter witn. whereof,wiehavehereunto rei 'lo I from the end of the' statorA longitudinallylrspectively set-our' handstherd dayof Feb 5 thereof, thereby forming aradial incliiio rela. ruary',1927,"a`lnd the 28th da 'of'March, 1927.

ytivoto said rotor, said rotor 'extending longii 4 fBOB RT POHL.;

tudinally beyond said stator, said group of'.` L. v `'HENRYREIST.

